Refactor: Move watch to ubi

watch is ubi specific functions, move it to ubi dir.

Tested: On the last commit of the patch series, run code update and
        factory reset on Witherspoon and all work fine.

Change-Id: Ia7f6b6de845ddd40e2a32ad626d3b7af9074c7f3
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/ubi/Makefile.am.include b/ubi/Makefile.am.include
index fba30d9..a836661 100644
--- a/ubi/Makefile.am.include
+++ b/ubi/Makefile.am.include
@@ -1,2 +1,3 @@
 openpower_update_manager_SOURCES += \
-	%reldir%/item_updater_ubi.cpp
+	%reldir%/item_updater_ubi.cpp \
+	%reldir%/watch.cpp